The device according to the invention may be utilized in connection with any liquid medium, comprising various liquids, suspensions, etc containing constituents desired to be filtered away. Even if the invention in no way is restricted thereto, a preferred application of the invention is in connection with dewatering of fibre suspensions. As fibres, cellulose fibres are primarily in view.
A device of the above mentioned type is previously known from the Swedish patent 8903128-0 (465 658). The filtrating layer is in the known device formed by a fibre cloth surrounding said at least one profiled element. When the filtrate comes through the filter cloth, it will thus enter into filtrate conduits formed between the filter cloth and said at least one profiled element. The filter cloth will thereby extend substantially flat over the peaks of the profilings of said at least one profiled element.
A disadvantage with such a filter cloth is that it is proportionately sensitive and may thus easily be damaged, which necessitates operation breakdowns in order to change filter cloths. The active surface of the filter is further limited to substantially the sum of the surface of both sides of the filter sector due to the fact that the filter cloth extends substantially flat on these sides.
The object of this invention is to further develop the device according to the prior art so as to simplify the embodiment of the filter sector and at the same time create the necessary conditions for increased filtration capacity of the filter sector.
This object is according to the invention achieved by that the profiled element itself forms the filtrating layer as a consequence of that said profiled element has a perforation permeable to said filtrate.
Thus, the need for a filter cloth will completely be eliminated; said at least one profiled element will itself by way of its perforation fulfil the filtrating function, which according to prior art was taking care of by means of a separate filter cloth. Further, a capacity increase is achieved by the solution according to the invention by means of that the total filter surface on the filter sector is increased as a consequence of the profiling of said at least one element.
The circumstance that the filtrating layer according to the invention thus will be formed by a profiled layer has surprisingly for a man skilled in the art turned out to not involve any difficulties regarding releasing material filtered away and deposited on the filter sector. This release takes in the preferred case place by means of water jet nozzles.
The projections/recesses formed by the profiling may have the character of elongated ridges/valleys, but may also be more point-like, for example in the form of bulges.